Method and apparatus for manufacturing and controlling the grain size of barium sulphate



Sept. 1944- G. L. BOULET METHOD AND APPARATUS FOR, MANUFACTURING AND CONTROLLING THE GRAIN SIZE OF BARIUM SULPHATE Filed Dec. 6. 1941 Ll F Gem/a1. Boulez INVENTOR M A TTORNE of the precipitate.

. Application December o, 1941, Serial 1 3- 2 a "7Clalms.

The present invention relates-tothe maniac-- ture of precipitated. barium sulphate (blanc flxe'),

and particularly to the'control of the grain size Precipitated barium sulphate has many uses,

- "Fig. l "is asectionalview of'one form of apbut the onewhich, i primarily of interest in j photographic papers, it is necessary to control the grain size very closely depending upon the l finish desired on.-the paper. It has been found that a fine-grain" size barium sulphate imparts a relatively high gloss to processed paper, while the larger-grain size material results in a surface that is dull even to a matte finish. i

In large scale production, precipitated barium sulphateisgusually made by mixing a soluble sul- 1 connection with the present inventionis its use .as a coating for photographic. papers. In the manufacture v of barium. s lphate for coating phate solution with a soluble barium salt." There:

are several known methodsof controlling the grain size of the precipitate 1l'lcluding, varying the concentration of the, solutions, varying the t mperature of thcsolutions and varying the v speed of stirring or agitation; at the time of contact of. the solutions] Any, or all, oi. the above-mentioned factors can'be-adiustedto meet certain conditions very nicely,but there are times,

7 especially in large scale manufacture control,

where more flexibility is desirable... Also, if, dur-' ing the manufacture of; the precipitate, any one of the above variables should get out of control it is desirable to be able'to compensate for it with a minimum of cost and inconvenience.

or conduit and i ma'qnam- 9 {Ne 1.5-. H

9 0 1. 9- with the accompanyingdrawing inwhich,

' paratus constructed in accordance with the pres.-

ent-inventiom; v v 2, is a top plan view of the apparatus in Fig. 1, and clearlyshowing ,the'manner ofadjusting the position of theeonduits toward and from the centerof the precipitating chamber,

Fig.3 'isa pun; viewshowingia modlfledform supporting and-mechanism,

4' is an elevatlonal viewof astandard settlingtnbe whichcan be usedvin deter mm .Dhat

Like reference I fer to ede a.

-, throughoutthe Briefly, in accordance with presentinven.

tion a barium salt solution and a soluble sulphate olution. are continuously introduced into a precipitating chamber where they aremixedgether d'ueto' the'action ofan agitator, or stirrer, in the chamber. The two' solutionsare introduced into, theprecipitating chamberon oppo-' site sides of the center thereof and the-points tionfrom a storage tank- It and asoluble sul- I Therefore, the primary objectgoi' thepresent invention is the provision of a method and apparatus for manufacturing precipitated barium sulphate by which the grain size of the precipitate can bevreadilyfcontrolled by merely varying the relative points of introduction of the solution into th precipitating chamber. 1

Another object is the'provision of a method and apparatus by; means of'which changes in rain size oiv the precipitate due to variations in] temperature of the solutions, concentration of the solutions, etc.,-can be readily accounted for in a'rapid andeflicient manner by a mere me- 7 chanical adjustment her. 7 e .v

The novel feature that! consider characterat the, precipitating chamistic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its methods' of operation, together with additional objects and advantage thereof, will best be understood from the following description of of introduction of the two solutions v =to and-from, the 'centertof the chamber to vary the grain'size of the precipitate. In accordance with the present invention,- pre cipitated barium sulphate (blanc flxe). is1manu- 1 facturedby introducing. a barium-sulphate soluphate solution from astorage tank l-l-icontinu ously into a precipitating chamber-12: preclpitating chamber'may be anopen'ended earth- 1 en-war'etilaasshown, in Fig; 1, verticallydisv P sed in an'earthen ware receptacle l3. I I ing into the center of theopen end of the pre- H f cipitating chamber I 2 lea shaft on -the' end of which thereis an impeller, Jorkagitator, ll which may be driven by any suitable means, such as motor M. The'lower endof the precipitating I chamber l2-is spaced fromthe-bottom of the receptacle l3 by afoot I5. formed onthe end of the tile so thatthe precipltateformedv-in'the chamber can flow out of the-bottomiof the tile and into the receptacle l3, as indicated by the flow arrows. It will be noticed that-the u per end of the chamber i2 is above the upper edge of the receptacle ll so that the barium sulphate will continually flow from the; chamber 12 into the receptacle l3 and spill over 'the'top thereof. This overflow of bariumsulphate precipitate will be caught in'a pant conducted when read connection to a settling tank, not shown, where the precipitate can settle from the liquid. I a

The solutions are conducted from the storage tanks in and II through pipes l8 and I1, respec tively, into conduits II and I9 adiustably mounted on a support 20 extending diametrically across the upper end of the precipitating chamber l2. Conduits II and i9 may be of any suitable shape so long as they serve to collect the solutions from the pipes and discharge them into the chamber, and for the purposes of illustration, I have shown them as funnels the outlets 2|, 22 oi which discharge the solutions'into the chamber.l2. The

conduit l8 for the barium salt solution is mounted on one side of the center of the chamber l2 and the conduit IQ for the soluble sulphate solution is mounted on the opposite side of the center of the chamber.

I have found that the grain size of the barium.

sulfate precipitate can be easily and efllciently controlled by moving the two conduits I8 and I9 toward and from the center of the chamber, and for this reason the conduits are supported so that they can be adjusted to and from the center of the chamber. As shown in Fig. l, the support 20 may be provided with a plurality of apertures 28 located on opposite sides of the center of the chamber from one to the other of which the conduits l8 and I 9 can be shifted on their respective sides of the chamber to -vary the grain size.

I have found that with both solutions entering at the closest position to the center of the chamber, the resulting grain size is as fine as possible with the particular solutions being used. Likewise, when the solutions are introduced into the precipitating chamber at the wall position on opposite sides of the center of the chamber, the resulting grain size is as large as possible with the solutions in use. Introducing the solutions at intermediate distances results in grain sizes between the above-mentioned fine grain and large grain.

I have found barium chloride (BaCla) and sodium sulphate (NazSOr) to be very satisfactory compounds for forming the solutions necessary to the manufacture of precipitated barium sulphate on a large scale primarily because each of these compounds is readily obtained at a reasonable price and they combine to form a solution ever, it is pointed out that the invention is not limited to the compounds specified, but covers the use of any soluble barium salt and soluble sulphate. 4000 pounds of barium chloride and 2600 pounds of sodium sulphate each dissolved in 3000 gallons of water, when mixed in the -ma"nner set forth, combine to form a very good yield of precipitated barium sulfate of good quality.

Determination of the grain sizeof barium sulphate can be carried out in several different ways. The method which I have found to be particularlv adapted for use in manufacturing and production control because of the ease and rapidity with which it can be carried out is described below. The solution containing the barium sulphate to be measured is introduced into a standard 250 cc. settling tube 21, as shown in F g. 4, to the upper -250 cc. mark. The neck of the tube is then closed with a ground 'glass stopper 28 and the contents thoroughly mixed by inverting the tube several times. The tube is thenplaced on a solid support and the time noted. After ten minutes the precipitate will have settled downwardly I have also found that a solution of and the reading is taken at the v.point to which the precipitate has settled in that time. reading the descending rather than the ascending scale.

Actually the tube is calibrated in 2 cc. steps so that itcan be read quite accurately, while I have shown only 25 cc. steps for purposes of clarity.

' By microscopic measurement it has been found that a sample that settles 36 cc. in ten minutes had a grain size of .25 mu, while one that set- .tled only co. in ten minutes measures .15 mu by the same method.

' The following table shows the results'of two test runs which prove that the grain size of the barium precipitate can be altered by changing 15 the positions of the point of the introduction of the two solutions into the precipitating chamher. The solutions used in the following tests were a barium chloride solution and a sodium sulphate solution of a given concentration using a settling time of ten minutes.

The above table shows that when the two solu- 30 tions were introduced at the most extreme position from the center of the precipitating chamber that more precipitate settledin a given time than when introduced at positions closer to the center of the chamber. Since the amount of precipitate settled in a. given time is a direct indication of the grain size of the precipitate, as set forth above in describing the settling test for determining the grain size, it will be obvious that the grain size changes from a maximum to'a minimum as the solutions are introduced nearer to the center of the precipitating chamber. A larger precipitating chamber or less concentrated solutions will give a wider range, while a smaller chamber or more concentrated solutions will shorten the range of grain sizes produclble.

I realize that it is not necessary to use the identical apparatus as set forth to obtain the same ends. Any similar set-up that would allow the solutions to mix in the manner above described, and any device that would permit the points of introduction of the solutions into the precipitating chamber to be adjusted to and from the center of the precipitating chamberso as to result in the above-mentioned grain size control, would come within the scope. of the present invention. By way of example of another modiilcation in the apparatus which would be suitable for carrying out the present invention, I have shown in Fig. 3 another manner in which the conduits for the solutions could be mounted on the top of the chamber to facilitate theiradjustment to and from the'center of the chamber. As shown in Fig. 3, the conduit l8 could be fixed to a slide 36 slidably mounted on rails 31 extending longitudinally of a support 20' having a slot 38 extending lengthwise thereof through which the outlet of the conduit extends into the chamber I2. Slide 36 is adapted to be nicely adjusted toward and from the center of the chamber along the support 20' by adjustment of a hand screw 39 engaging a threaded eye-40 fixed to the slide. Instead of having the conduits i8 and 19 in the form of funnels having the mouths large enough to catch the flow fronrthe pipes I6 and H in any position chadiustment, it will be obvious that the pipes could be made flexible and have their ends directly I connected to a conduit movable along the support 20 to permit them to-be adiusted to and' precipitated barium sulphate by controlling the stirrer speed; but such a method" of control in a manufacturing set-up is rather inconvenient.

' Temperature adjustments probably" would do the same thing, but that also w'ouldlbe inconvenient for the reason that it-would be slow and diiilcult to closely regulate. Varying the 'con-' centration of the solutionsalso might do it, but

'- here also it would beim'practical and inconvenient in a manufacturing set-up for large scale production. From-the above description it willbe readily apparent ,to one skilled in the art with the predetermined grain slze,-. and :noting' the difference between the two, and then moving the points of introduction of the solutions toward it and away from one another during the 'produc-l' tion run until the'sele'cted -predetermlned".grain size obtained, thegrain --size varying' l n direct proportion with the variation in the: spacing of the points of introductionl'relative: to'f'one an? other, other conditions being, maintained ,un-'

changed.

3. In a method of makingbarium jsulphate' and controlling the grain size thereof 'the'st'eps'jf of selectingapredeterminedlgrain slzefior'the-Q barium. sulphate, continuously introducing a the barium sulphate formed andcomparing it barium chloridesolutionf and asodium' sulphate 11 1 i I solution into an enclosure at separatedpoints,

' continuously agitating the solutions within the I v enclosure so as to mlxflthe two togetherydeterthat by the use of the'her'ein' disclosed method and apparatus the, grainsize 'oflprecipitated barium sulphate canbe readily controlled over I a substantially wide range-by a mere mechanical 2 adjustment or the apparatus and a change in grain size can, therefore, beaccomplishedzquickly and efllciently by an unskilled o'perator.

Furthermore, by the use-or this method of grain size control any change in the desired grain sizedue to variations in the temperatures of for other unforeseen reasons, can be quickly and precipitating chamber to correct for such yathe solutions, concentration of the solutions or riation. The methodis so simple that any existing apparatus could be readily changed in view of the teachings of this'disclosure to carry it out in the manner setforth. V, Although I have shown and described certain specific embodiments oi, my invention, I am fully aware that many modifications thereof 'are posslble" My invention therefore to be redetermined grain'size and noting the difference stricted except insofar as is necessitated by the scope of the appended claims.

ent of the United States is:

v 1. In a method of making "barium sulphate and controlling the grain size thereof the steps mining the grain size 'of'the barium sulphate two, and then moving the points of introduction of the two solutions relative to one anotherto vary the (spacing therebetween ,untll thelpre l determined grain size is obtained, the grain size .va'rying'in direct proportion with the variation" in the spacing of the points of introduction of the two solutionsv relative to one another; other conditions being maintained unchanged.

4. A method of making'precipitated barium sulphate and controlling the'grain sizethereof comprising the'steps of selecting apredetermined grain size for the barium sulphate, continually introducing a barium chloride solution contain-.

mg 4000 lbs. of barium chloride and a sodium sulphate solution containing 2600 lbs. of sodium sulphate into an enclosure at separated :points on opp site sides of the center of the enclosure,

agitating the solutions within the enclosure with a circular motion about the center of the enclosure, determining the grain size of the barium sulphate formed and comparing it with the preintroduction of the two solutions toward and away from thecenter of the enclosure during of selecting a predetermined grain size for the 1 barium sulphate, continuously introducing a I barium salt solution and asoluble sulphate solutionin'to an'enclosure at-separated points and agitating the solutions within the enclosure, determining the grain'size of the barium sulphate formed and comparing it with the predetermined grain sizefand noting the difference between the-two', and .then moving the points of introduction of the two solutions toward and away from one another until the predetermined grain size is obtained, the grain size varying in direct proportion with the variation in the spacing of the points of introduction of the two solutions relative to one another.

2. In a method of makingbarium sulphate and controlling the grain size thereof the steps of selecting apredetermined grain size for the barium sulphate} continuously introducing a barium salt solution and'a soluble sulphate solution into an enclosure at separated points on opposite sides of the center of the enclosure, and agitating the solutions within the enclosure with a circular motion, determining the grain size of the production run until the predetermined grain size is obtained, the grain size varying in direct proportion with the variation in the spac ing of the pointsof introduction of the solutions relative to one another, other conditions being maintained unchanged.

5. In a method of making barium sulphate and controlling thexgrain size thereof the steps of continuously introducing a barium salt solution and a soluble sulphate solution into an enclosure at separated points, agitatingthe solutions. within the enclosure, determining the grain size'of the barium sulphate produced, selecting a predetermined grain size smaller than that produced, and moving the points of introduction of the two solutions toward one another until the predetermined selected grain size is obtained, other conditions being maintained unchanged. I Y

6. In a method'of making barium sulphate and controlling the grain size thereof the steps of continuously introducing a barium saltsolution anda soluble sulphate solution into an enclosure at separated points, agitating the solutions within the enclosure, determining the grain size of the barium sulphate produced, selecting a predetermined grain size larger than that'prooi the two solutions away from one another until the predetermined selected grain size is obtained, other conditions being maintained unchanged.

'1. An apparatus for carrying out reactions involving the formation of a precipitate and controlling the grain size thereof, comprising a vertically disposed open-ended circular precipitating chamber, a support extending across the upper end oi said chamber and provided with a plurality of apertures extending along said support on each side of the center thereof, the order of spacing of said apertures being the same on each side of the center oi. the support, a pair of liquid receiving means removably supported in the apertures 01' said support, at least two sources of supply of reacting solution, pipe means connected to said sources of supply and associated with said liquid receiving means and agitating means in said chamber.

GERALD L. BOULET. 

